JP3340855B2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler provided in OA equipment and the like.

[0002]

2. Description of the Related Art Conventionally, in a comfortable office environment (especially an environment relating to quietness), operating sounds and blowing sounds generated by OA equipment used in an office such as a copying machine become noise. As a means for preventing such noise from leaking out of the device, a resonance type silencer, particularly a Helmholtz resonator is known. Here, the operation principle of the Helmholtz resonator will be described. Helmholtz resonator 1 is shown in FIG.
As shown in FIG. 4 (a), a length Tb,
The short pipe 3 having a cross-sectional area Sb is configured by being connected thereto, and the opening of the short pipe 3 is connected to another space (for example, an OA device serving as a noise generation source). Now, assuming that sound pressure acts on the inlet of the short tube 3 from the external space, the medium (air) in the short tube 3 moves integrally, and pressure fluctuation occurs in the medium in the cavity 2. Assuming that the medium in the short tube 3 is a mass point and the pressure change due to the volume change of the air in the cavity 2 is a spring, this phenomenon is equivalent to a mass point-spring model of a dynamic system.
Resonance occurs at a certain frequency (hereinafter referred to as Helmholtz resonance frequency). At this Helmholtz resonance frequency, the acoustic energy inside the cavity 2 is confined,
The sound is muted for the external space. In this case, the Helmholtz resonance frequency fr is expressed by equation (1).

[0003]

[Outside 1]

As shown in FIG. 14B, when the Helmholtz resonator 1 is connected to a tube 4 having a cross-sectional area S, the silencing effect _ATT is expressed by equation (2).

[0005]

[Outside 2]

FIG. 14C is a graph of the equation (2). Here, it is set as in equation (3).

[0007]

[Outside 3]

Accordingly, from the relations of the equations (1) to (3), the Helmholtz resonator 1 having a sound deadening effect for the same Helmholtz resonance frequency fr has a larger sound deadening effect as the value of α becomes larger. It turns out that it becomes.

A known example of silencing using the above-described Helmholtz resonator is to provide a Helmholtz resonator in a paper feed path of a printer to put a paper in and out of the printer (JP-A-2002-163686). Japanese Patent Laid-Open No. 63-239076) and a gear portion provided adjacent to a developing unit of a laser printer device is covered by a soundproof cover, and a Helmholtz resonator is connected to one end of the soundproof cover to mute the sound. There is one that enhances the effect (see JP-A-4-469).

[0010]

In order to minimize the noise generated by the OA equipment and the like outside the equipment, the OA
It is desirable to surround the entire device with exterior components or the like. However, in a copying machine or the like, an opening for discharging paper to the outside and an opening for inflow and outflow of cooling air for avoiding a rise in temperature inside the device are indispensable. In this case, there is naturally a limit to noise reduction by simply surrounding the entire device provided with the paper discharge opening and the air blowing opening.

Also, in the above-mentioned known example, arranging the Helmholtz resonator in the feed passage for taking in and out the paper may cause a paper jam or the like, and the gear portion serving as a noise source is soundproofed. Enclosing with a cover may cause a rise in the temperature inside the device.

[0012]

According to the first aspect of the present invention,
A basic silencer having an inflow port through which air discharged from a device that is a source of noise flows, and a discharge port that discharges the air flowing in through the inflow port to the outside, forming a fixed space through which the air flows. Room, a partition plate having a circulation hole for partitioning the space of the basic sound deadening room, a closed space sound deadening room partitioned by the partition plate and configured to muffle the noise by a Helmholtz resonance frequency, and An air flow passage formed along the partition plate and guiding the inflowing air to the discharge port, and constitutes a muffler;
The length of the air flow passage from the mouth to the outlet is L, the sound speed is c,
Assuming that a natural number is n, the length L of the basic silencer and
A plurality of Helmholtz resonance frequencies fr in the sound chamber were set to have a relationship of L {c} (4 * fr) * (2 * n-1) .

According to a second aspect of the present invention, in the first aspect of the present invention, at least two partition plates having a flow hole are provided, and these partition plates partition a space in the basic sound deadening chamber on both sides sandwiching an air flow passage. A plurality of silencing chambers were formed at positions facing each other.

[0014] The invention according to claim 3 is a noise source.
Inlet and the inflow of air exhausted from equipment
A discharge port for discharging the air that has flowed in through the port to the outside.
And a basic silencing chamber in which a certain space through which the air flows is formed.
And a partition with a circulation hole that partitions the space of this basic silencer
And the Helmhol
Noise in a closed space to mitigate the noise by using two resonance frequencies
And a partition formed along the partition plate for partitioning the sound deadening chamber.
From the air flow passage leading the inflowing air to the outlet.
Becomes, provided movably the partition plate to vary the volume of the closed space of the muffler chamber, the flow holes variably freely formed to vary the cross-sectional area of the flow holes of the partition plate, the base silencing chamber air
The distribution wall that forms the flow passage is located between the inlet and the outlet.
It is provided movably along the air flow direction .

[0015] The invention according to claim 4 provides the invention according to claim 3.
, At least two partition plates with circulation holes
These partitions separate the space inside the basic sound deadening room.
Plural silencing chambers are placed on opposite sides of the airflow passage
Formed.

According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, there is provided a mode detecting device for detecting an operation state of a device on standby or in operation, and controlling a moving amount of the partition plate with respect to the operation state. And a partition plate moving device for moving the controlled partition plate.

The invention according to claim 6 is the invention according to claim 3 , 4 or
5. In the invention as set forth in claim 5, a noise amount detection device for detecting a noise amount of the device, a partition plate movement control device for controlling a movement amount of the partition plate according to the noise amount, and a partition for moving the controlled partition plate A plate moving device was provided.

[0018] According to a seventh aspect, the preceding claims 3 6
In the invention according to any one of the above, a distribution wall movement control device that controls the amount of movement of the distribution wall formed in the air flow passage in the air circulation direction, and a distribution wall movement device that moves the controlled distribution wall Was provided.

[0019]

According to the first aspect of the present invention, the air containing sound waves corresponding to the noise emitted from the equipment is guided into the basic sound deadening chamber through the inflow port, and the Helmholtz resonator in which the sound waves are separated by the partition plate. The sound energy of the sound wave is confined and silenced in the silencing chamber through the circulation hole, and the thus silenced air is discharged from the air flow passage to the external space through the outlet. . In addition, several Helmholtz resonance circuits in the sound deadening room
Varying the length L of the basic silencing chamber with respect to the wave number fr
The plurality of Helmholtz resonance frequencies f in the sound deadening room
r and the dip circumference created in the space of the basic silencer room of length L
The wave number can be different.

According to the second aspect of the present invention, the sound waves are silenced in a plurality of silence chambers located on both sides of the air flow passage,
The air travels smoothly along the air flow passage, which enhances the noise reduction effect without impairing the air flow.

According to the third aspect of the present invention, the device
Air containing sound waves corresponding to the noise generated
The sound is guided into the basic sound deadening room, and the sound waves are separated by the partition plate
Through the flow holes that make up the Helmholtz resonator
Guided into the sound chamber, the acoustic energy of the sound
Gee is trapped and silenced, and thus silenced
The exhausted air is discharged from the air passage to the external space through the discharge port.
Will be issued. In addition, by moving the partition plate, the volume in the sound deadening chamber is changed, and by changing the flow hole, the diameter of the hole, that is, the cross-sectional area is changed. Soshi
To move the distribution wall of the airflow passage in the airflow direction.
And by, changing the body volume of the space occupied by the basic muffling chamber, its
Arbitrarily change the drop frequency created in the basic silencer
It is.

According to the fourth aspect of the invention, the sound wave is empty.
Muffled in multiple silencers located on both sides of the airflow passage,
The air proceeds smoothly along the air flow passage,
This enhances the silencing effect without compromising airflow
Can be

According to the fifth aspect of the present invention, when the standby state is detected by the mode detecting device, the partition plate is moved so that all the frequencies generated in the plurality of sound deadening chambers are made equal to reduce fan noise and the like. When the operating state is detected, the partition plate is moved so that the frequencies generated in the plurality of sound deadening chambers are different from each other, thereby reducing various noises other than the fan noise.

According to the sixth aspect of the present invention, the frequency generated in the plurality of sound deadening chambers can be changed arbitrarily by moving the partition according to the noise amount detected by the noise amount detecting device, thereby changing the noise frequency. Also reduce noise.

According to the seventh aspect of the present invention, by controlling the movement of the distribution wall using the distribution wall movement control device and the distribution wall movement device, the dip frequency produced in the basic sound deadening room can be reduced by the Helmholtz resonance frequency of the sound deadening room. Can be changed to a value that does not match

[0026]

A first reference example of the embodiment of the present invention that describes with reference to FIGS. As shown in FIG. 2, an outer cover 5a of an OA device 5 (for example, a copying machine) as a device is provided with a ventilation port 6 for cooling the inside of the device. A fan 7 for exhausting air is mounted. In this case, the sound of air blown by the fan 7 or the operation sound inside the device is a source of noise. The exterior cover 5a has a length L, which covers the ventilation opening 6.
A basic silencing chamber 8 having a fixed space of width W and thickness T is mounted. An inlet 9 is formed in the basic silencing chamber 8 at a position facing the ventilation opening 6, and an outlet 10 is formed below the air outlet 9 for discharging air to the outside.

FIG. 1 shows the external structure of a muffler in which a basic muffler chamber 8 is formed. This basic silencer 8
Inside, a partition plate 11 having a thickness Tb is disposed along the L direction. The partition plate 11 has a flow hole 12 having a cross-sectional area Sb. Further, in the basic noise reduction chamber 8, the partition plate 1 is arranged along a direction T orthogonal to the partition plate 11.
3 are provided. The partition plate 11 and the partition plate 13
By dividing the inner space by the above, for example, a sound deadening chamber 14 composed of a closed space having a volume V is formed on the opposite side of the inflow port 9. This silencer 14 constitutes a Helmholtz resonator that reduces noise.

Further, by dividing the inside of the basic silencing chamber 8 by the partition plate 11, the space between the partition plate 11 and the inner wall along the L direction of the basic silencing chamber 8 is formed as an air flow passage 15. I have. The lower part of the air flow path 15 is the discharge port 10 and discharges air to the outside.

In such a configuration, the air exhausted from the fan 7 on the OA equipment 5 flows into the air flow passage 15 of the basic sound deadening chamber 8 through the inflow port 9. Then, the acoustic energy is guided through the communication hole 12 into the sound deadening chamber 14 constituting the Helmholtz resonator. At this time, circulation hole 1
2, the thickness Tb of the partition plate 11 and the volume V can be appropriately adjusted to produce the Helmholtz resonance frequency fr represented by the above equation (1). Cause a resonance phenomenon,
Sound energy can be confined. As a result, the sound is muted in the space outside the muffling chamber 14, and thereafter, the air is discharged from the air flow passage 15 to the outer space through the lower outlet 10, so that the noise of the OA equipment 5 is reduced in the outer space. The state is reduced. Accordingly, since the air is exhausted to the outside through the air flow passage 15 while the sound wave is silenced in the silencing chamber 14 of the closed space constituting the Helmholtz resonator, a sufficient silencing effect can be obtained. This also gives
Since the flow of air is not impaired, a rise in temperature inside the apparatus, paper jams, and the like can be eliminated.

Next, described with reference to the second reference example of the present invention in FIGS. The description of the same parts as those in the first embodiment is omitted, and the same parts are denoted by the same reference numerals.

As shown in FIG. 3, in the basic sound deadening chamber 8,
Two partition plates 11 each having a circulation hole 12 are arranged in parallel along the L direction. These partition plate 11 and partition plate 13
Thus, two muffling chambers 14 are formed at opposing positions on both sides of the air flow passage 15.

In such a configuration, first, as shown in FIG. 3, the air sent from the OA equipment 5 is guided into the basic noise reduction chamber 8 through the inflow port 9, and the acoustic energy is transmitted to both sides of the air flow path 15. It is confined in the provided silencing room 14. At this time, the Helmholtz resonance frequency fr can be arbitrarily changed by arbitrarily selecting the thickness Tb of the two partition plates 11 provided on both sides and the volume V of the sound deadening chamber 14. In this case, the noise reduction effect at the same resonance frequency can be increased by making the noise reduction chambers 14 on both sides the same size. Further, by making the noise reduction chambers 14 on both sides different in size, the noise reduction effect for the two resonance frequencies can be obtained. A silencing effect is obtained. Thereafter, the air thus silenced travels through the air flow passage 15 and is discharged from the discharge port 10. Since the plurality of silencing chambers 14 are arranged on both sides of the air flow passage 15, the silencing effect can be enhanced without disturbing the air flow.

Further, as shown in FIG. 4, a plurality of circulation holes 12 are formed in the partition plate 11, and a large number of noise reduction chambers 14 are provided in the basic noise reduction chamber 8 by partitioning with the partition plate 13. Good. By increasing the number of the muffling chambers 14 in this way, more different resonance frequencies can be set, and the muffling effect can be further increased.

Next, described a third exemplary embodiment of the present invention with reference to FIG. The description of the same parts as those in each of the embodiments is omitted, and the same reference numerals are used for the same parts.

In order to change the cross-sectional area Sb of the flow hole 12 formed in the partition plate 11, an adjusting partition plate 16 movable in a direction perpendicular to the flow hole 12 is provided. Also,
The partition plate 13 is movable in the air flow direction (L direction).

In such a configuration, the adjusting partition 16
And the partition plate 13, the cross-sectional area Sb of the flow hole 12 and the volume V in the sound deadening chamber 14 can be changed. This is equivalent to changing two Helmholtz resonance frequency fr variables shown in equation (1). As a result, the resonance frequency for reducing noise can be set arbitrarily and broadly without changing the structure of the entire device.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.
It described with reference to. The description of the same parts as those in each of the embodiments is omitted, and the same reference numerals are used for the same parts.

This muffler includes a mode detector 17,
A partition plate movement control device 18 and a partition plate movement device 19 are provided. In this case, the mode detection device 17
The operation state of standby and operation of the device 5 is detected. Further, the partition plate movement control device 18 controls the amount of movement of the partition plate 13 (see FIG. 5) in accordance with the standby and operating states. Further, the partition plate moving device 19 actually moves the partition plate 13 in the L direction.

In such a configuration, even when the power of the OA device 5 is in the ON state, the noise during the stand-by time when the OA device 5 is not operating is mainly fan noise. FIG. 7 shows an example of noise analysis in the 1/3 octave band during standby when the fundamental frequency of the fan 7 is around 500 Hz. In this case, in the frequency analysis of the fan noise, <1
The number of rotations per second x the number of birds>
There is a peak at a harmonic component that is an integral multiple of this, and in this example, it can be seen that the peak is particularly large in the band of 500 Hz and twice the frequency of 1 KHz. FIG. 8 shows an example of noise analysis during operation. It can be seen that this operation includes various frequency components over a wide range in addition to the fan noise. Therefore, in order to effectively reduce the noises during the stand-by and the operation, it is necessary to reduce the frequency components corresponding to the fan noise during the stand-by, and to reduce various frequency components during the operation. Is desirable.

Therefore, the OA is detected by the mode detecting device 17.
A signal from which the standby or operation mode of the device 5 can be determined is extracted. When the standby mode is detected, the partition plate 13 is moved so that the resonance frequencies of all the silencing chambers 14 constituting the Helmholtz resonator match the fan noise frequency so as to reduce the fan noise. Further, when the mode at the time of operation is detected, the partition plate 13 is moved so that the resonance frequencies of the respective muffling chambers 14 are different so as to correspond to various frequencies. In this case, the amount of movement of the partition plate 13 is controlled by the partition plate movement control device 18, and the actual movement of the partition plate 13 in a predetermined direction is performed by the partition plate movement device 19. Accordingly, since the movement of the partition plate 13 is controlled in accordance with the mode state in this manner, the noise can be reduced intensively for the fan noise during standby and a wide range of frequencies during operation, and the noise can be further reduced. It can be reduced effectively.

Next, it described a fifth reference example of the present invention with reference to FIG. The description of the same parts as those in each of the embodiments is omitted, and the same reference numerals are used for the same parts.

The noise reduction device includes a noise amount detection device 20,
A partition plate movement control device 21 and a partition plate movement device 22 are provided. In this case, the noise amount detection device 20
The noise amount of the device 5 is detected. Partition plate movement control device 21
Controls the amount of movement of the partition plate 13 (see FIG. 5) according to the amount of noise. The partition moving device 22 actually moves the partition 13 along the L direction.

In such a configuration, the frequency component of the noise generated by the machine such as the OA equipment 5 changes due to aging or load fluctuation. Therefore, the noise amount at which the frequency component changes is detected by the noise amount detection device 20, and the partition plate 13 is moved using the partition plate movement control device 21 and the partition plate movement device 22 so that the noise amount is reduced. That is, the partition plate 13 is moved so that the resonance frequency of the muffling chamber 14 matches the changing frequency component. Thereby, the OA equipment 5
The noise can be effectively reduced even when the noise frequency fluctuates due to the temporal change of the noise.

Next, explaining a first embodiment of the present invention with reference to FIG. The description of the same parts as those in each of the above reference examples is omitted, and the same reference numerals are used for the same parts.

The length L of the air flow passage 15 of the basic silencer 8
And a plurality of Helmholtz resonance frequencies fr in the silencer 14
Is defined as: L {c} (4fr) × (2n-1) (4) where c is the speed of sound and n is a natural number.

In such a configuration, FIG.
Shows how the noise reduction effect (muffling effect) of the basic muffling room 8 changes with a change in the length L of the basic muffling room 8, that is, a change in the frequency. At this time, the drop frequency fn of the noise reduction effect is expressed as fn ≒ c ÷ (4L) × (2n−1) (5). At this drop frequency fn,
Resonance occurs in the basic silencer 8, increasing noise and deteriorating the noise reduction effect. FIG. 10A shows an example in which the dip frequency fn and the Helmholtz resonance frequency fr in the sound deadening chamber 14 are set to the same frequency, whereby the sound deadening effect of the entire sound deadening apparatus is obtained by adding both frequencies. Therefore, noise is not reduced.

Therefore, the length L of the basic silencer 8 is changed so that the Helmholtz resonance frequency fr of the silencer 14 does not coincide with the drop frequency fn of the basic silencer 8. FIG.
0 (b) is the Helmholtz resonance frequency fr of the sound deadening chamber 14
= 500 Hz, fr and fn do not match,
By referring to the equation (4), for example, L = c ÷ (4fr) × (2n) (6) By setting c = 345 m / sec, a length L = 345 mm can be obtained. The shape of the basic silencing chamber 8 is created so as to be L. As a result, even if both frequencies (fr, fn) are added, the noise reduction effect of the entire noise reduction device is not impaired, and noise can be effectively reduced.

Next, it described a second embodiment of the present invention with reference to FIG. The description of the same parts as those in each of the above reference examples and embodiments is omitted, and the same reference numerals are used for the same parts.

The flow wall 23 forming the air flow passage 15 of the basic silencing chamber 8 is provided movably along the air flow direction (L direction) between the inflow port 9 and the discharge port 10.

In such a configuration, the distribution wall 23 is
By moving in the direction, the length L, that is, the volume, of the basic silencer 8 can be changed, and the drop frequency fn of the equation (5) can be set arbitrarily. This allows
Even if the Helmholtz resonance frequency fr in the sound deadening chamber 14 fluctuates, the drop frequency fn of the basic sound deadening chamber 8 can be freely changed, so that the Helmholtz resonance frequency fn and the drop frequency fn can be avoided from being matched. Therefore, the sound deadening room 1
The silencing effect in the interior 4 is not canceled by the silencing effect of the basic silencing chamber 8, and the noise can be reduced more effectively.

Next, we described a third embodiment of the present invention with reference to FIG. The description of the same parts as those in each of the above reference examples and embodiments is omitted, and the same reference numerals are used for the same parts.

A flow wall (WT wall) movement control device 24 for controlling the amount of movement of the flow wall 23 (see FIG. 11) forming the air flow passage 15 in the air flow direction (L direction) is provided. . A distribution wall (WT wall) moving device 25 that actually moves the distribution wall 23 in the L direction is connected to the distribution wall movement control device 24. Here, the distribution wall movement control device 24 controls the movement amount of the partition plate 13 in accordance with the standby / operating state and the noise amount.
(See FIGS. 6 and 9).

In such a configuration, when the Helmholtz resonance frequency fr in the sound deadening chamber 14 fluctuates, the distribution wall movement control device is set so that the drop frequency fn of the basic sound deadening chamber 8 does not match the Helmholtz resonance frequency fr. 2
The distribution wall 23 is automatically moved in the L direction using the fourth and fourth distribution wall moving devices 25. This makes it possible to immediately respond to a sudden change in the Helmholtz resonance frequency fr and eliminate a sudden increase in noise.

Next, described <br/> the sixth reference example of the present invention. The description of the same parts as those in each of the embodiments is omitted, and the same reference numerals are used for the same parts.

In this silencer, the cross-sectional area Sb
First movement control means for controlling the movement of the partition plate 13 so that the ratio between the volume V of the noise reduction chamber 14 and the volume V of the noise reduction chamber 14 is constant. There is provided a second movement control means for controlling the movement of the partition plate 13 so that both of these variables have large values while maintaining the same (not shown).

In such a configuration, the movement control of the partition plate 13 by the first and second movement control means will be described. First, the Helmholtz resonance frequency fr of the sound deadening chamber 14
To the frequency of the target noise. According to equation (1), for one Helmholtz resonance frequency fr,
Since Sb and V can be selected infinitely so that (Sb / V) is constant, if a constant (Sb / V) is obtained, the values of Sb and V are set to any combination. May be. In this case, Sb is determined by moving the adjustment partition plate 16 (see FIG. 5) in a direction perpendicular to the flow hole 12, and V is determined by moving the partition plate 13 in the L direction (first movement control means). . Next, the Helmholtz resonance frequency fr is adjusted in such a manner as to match the noise frequency so as to increase the silencing effect. In order to make such an adjustment, the noise reduction effect A _TT is expressed by Sb × V from equations (2) and (3).
Can be achieved by increasing both variables at the same ratio while keeping (Sb / V) constant. Thus, it is possible for the same Helmholtz resonance frequency fr, increase most silencing effect A _TT muffler chamber 14.

Next, we explain seventh exemplary embodiment of the present invention FIG. 13 for. The description of the same parts as those in each of the embodiments is omitted, and the same reference numerals are used for the same parts.

[0058] The inner wall of the air flow passage 15 of the basic muffler chamber 8, the sound absorbing material 26 is installed. As the sound absorbing material, for example, a gypsum board or a wool board can be used. Accordingly, noise propagating in the air flow passage 15 of the basic silencing chamber 8 can be absorbed by the sound absorbing material 26, so that the amount of noise leaking from the outlet 10 of the basic silencing chamber 15 to the outside can be further reduced. it can. Further, in this case, since the sound absorbing material 26 is provided on the inner wall of the air flow passage 15, it is possible to perform stable exhaust without disturbing the flow of air.

[0059]

According to the first aspect of the present invention, a closed silence chamber constituting a Helmholtz resonator is created by partitioning the board silence chamber with a partition plate having a circulation hole. The sound wave corresponding to the generated noise is guided into the sound deadening chamber through the inflow port and resonated by the Helmholtz resonance frequency, whereby the acoustic energy of the sound wave can be confined in the sound deadening chamber. At the stage of discharge, the muffler is in a muffled state, and a sufficient muffling effect can be obtained.In addition, since the air is exhausted through the air flow passage, the flow of the air is not impaired, whereby A temperature rise or the like can be eliminated, and a highly reliable silencing device can be provided. In addition, a basic silencer of length L
Frequency and multiple Helmholtz in the sound deadening room
Conditional expression is set so that resonance frequency fr does not match
So, the silencing effect in the silencing room is the same as the silencing effect in the basic silencing room.
Will not be canceled by
Noise by maintaining the noise reduction effect of the entire device above a certain value.
Can be effectively reduced.

According to the second aspect of the present invention, since a plurality of silencing chambers are provided facing both sides of the air flow passage, the silencing effect can be enhanced without obstructing the air flow. By forming such a plurality of silencing chambers with the same volume or different volumes, it is possible to cope with noise of a single or a plurality of types of frequencies, and it is possible to further improve the silencing effect.

According to a third aspect of the present invention, there is provided a substrate sound deadening chamber.
Helmho is divided by a partition plate with through holes.
Create a closed-space silencer that composes a Ruth resonator
A sound wave corresponding to the noise emitted from the device.
Guided into the sound deadening room through the entrance to Helmholtz resonance frequency
Make the sound more resonate, and the acoustic energy of the sound wave
Can be trapped, which allows air to flow
The sound is silenced when it is discharged to the outside through the discharge port.
And the sound is sufficiently muted.
Also, since air is exhausted through the airflow passage, the airflow
Damage to the device
High reliability silencer
Can be provided. In addition, since the partition plate is movably provided, the volume of the closed space in the sound deadening chamber can be changed, and since the flow hole is variably formed, the cross-sectional area of the flow hole can be freely changed. Since the frequency for reducing noise can be set arbitrarily and broadly without changing the structure of the entire device, various types of noise can be dealt with, and the use of the device can be further expanded. Then, the distribution wall of the air flow passage is
So that it can move freely in the direction
The drop frequency can be set arbitrarily.
And the Helmholtz resonance frequency fluctuates in the sound deadening room.
Since the drop frequency of the sound deadening room can be changed,
Make sure that the Rutz resonance frequency matches the drop frequency.
And the noise reduction effect in the sound deadening room
It is not canceled out by the sound effect and always effectively reduces noise
Can be done.

According to a fourth aspect of the present invention, a plurality of muffling rooms are provided.
Since the air flow passage is provided on both sides of the air passage,
This can enhance the sound-muffling effect without obstructing the flow.
Multiple silencers with the same volume or different volumes
By shaping, noise of single or multiple frequencies
Can be dealt with, and the silencing effect can be further improved.
Can be.

According to a fifth aspect of the present invention, the standby state or the operating state of the device is detected by the mode detection device, and the movement of the partition plate is controlled by the partition plate movement control device and the partition plate movement device in accordance with the mode state. With this configuration, the noise can be reduced intensively with respect to the fan noise during standby and a wide range of frequencies during operation, and thereby more effective noise reduction can be performed for each mode.

According to the sixth aspect of the present invention, the mode detection device detects the noise amount of the device, and the partition plate movement control device and the partition plate movement device control the movement of the partition plate according to the noise amount. In addition, noise can be further effectively reduced even when the noise frequency fluctuates due to aging of the device.

According to the seventh aspect of the present invention, the movement of the flow wall formed in the air flow passage in the air flow direction is automatically controlled using the partition plate movement control device and the partition plate movement device. Therefore, even if the Helmholtz resonance frequency in the sound deadening room fluctuates, the drop frequency of the basic sound deadening room can be changed immediately so as not to match the Helmholtz resonance frequency in response to the fluctuation, and a sudden increase in noise can be suppressed. You can always create a quiet environment.

[Brief description of the drawings]

1 is a perspective view showing an external configuration of the muffler as a first reference example of the present invention.

FIG. 2A is a cross-sectional view illustrating a structure of a basic silencing room attached to an OA device, and FIG. 2B is a perspective view illustrating an external configuration of the basic silencing room.

3 is a perspective view showing an external configuration of a second silencer which is a reference example of the present invention.

FIG. 4 is a perspective view showing an external configuration of the muffler.

FIG. 5 is a sectional view showing a state of movement of a partition plate according to a third reference example of the present invention.

FIG. 6 is a block diagram showing a fourth reference example of the present invention.

FIG. 7 is a characteristic diagram illustrating an example of noise analysis during standby.

FIG. 8 is a characteristic diagram illustrating an example of noise analysis during operation.

FIG. 9 is a block diagram showing a fifth reference example of the present invention.

FIG. 10 shows a first embodiment of the present invention;
(A) is a waveform diagram showing the noise reduction effect when the Helmholtz resonance frequency of the sound deadening room and the drop frequency of the basic sound deadening room match, and (b) is the waveform of the Helmholtz resonance frequency of the sound deadening room and the drop frequency of the basic sound deadening room. FIG. 9 is a waveform chart showing a noise reduction effect when the values are different from each other.

FIG. 11 is a perspective view showing a state of movement of a distribution wall according to a second embodiment of the present invention.

FIG. 12 is a block diagram showing a third embodiment of the present invention.

FIG. 13 is a cross-sectional view showing a state in which a sound absorbing material according to a seventh reference example of the present invention is provided in a basic sound deadening chamber.

14A and 14B show a conventional example, in which FIG. 14A is a schematic diagram showing a basic configuration of a Helmholtz resonator, FIG. 14B is a schematic diagram showing a configuration of a Helmholtz resonator connected to a tube, and FIG.
FIG. 4 is a waveform diagram showing a sound deadening effect of the Helmholtz resonator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 5 Equipment 8 Basic noise reduction room 9 Inflow port 10 Outlet 11 Partition plate 12 Distribution hole 13 Partition plate 14 Noise reduction room 15 Air flow path 17 Mode detection device 18 Partition plate movement control device 19 Partition plate movement device 20 Noise amount detection device 21 Partition Plate movement control device 22 Partition plate movement device 23 Distribution wall 24 Distribution wall movement control device 25 Distribution wall movement device 26 Sound absorbing material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-94278 (JP, A) JP-A-4-469 (JP, A) JP-A-1-169194 (JP, A) JP-A-1- 273816 (JP, A) JP-A-6-159174 (JP, A) JP-A-61-110818 (JP, U) JP-A-62-1101289 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/20 G03G 21/16-21/18 G03G 21/00 370-540 B41J 29/00-29/70 H05K 7/20 G10K 11/00-13/00

Claims (7)

(57) [Claims] 1. An air inlet through which air discharged from a device that is a source of noise flows, and an outlet through which the air flowing through the inlet is discharged to the outside. A formed basic noise reduction chamber, a partition plate having a circulation hole for partitioning the space of the basic noise reduction chamber, a closed noise reduction chamber partitioned by the partition plate and configured to muffle the noise by a Helmholtz resonance frequency, wherein Ri Do is formed along the partition plate the inflow air from the air flow passage leading to the outlet, the flow of the basic muffling chamber dividing the muffling chamber
The length of the air flow passage from the inlet to the outlet is L, and the speed of sound is
c, where n is a natural number, the length L of the basic silencing chamber
And a plurality of Helmholtz resonance frequencies fr in the sound deadening room
The, L ≠ c ÷ (4 × fr) muffler, characterized in that set in relation × (2 × n-1) . 2. A method according to claim 1, wherein at least two partition plates having flow holes are provided, and the partition plates partition a space in the basic noise reduction chamber to form a plurality of noise reduction chambers at opposing positions on both sides sandwiching an air flow passage. The muffler according to claim 1, wherein: 3. Emissions from equipment that is a source of noise
An inlet into which air flows and the air flowing through the inlet
And a discharge port for discharging air to the outside.
A basic noise reduction room with a fixed space,
A partition plate having a circulation hole for partitioning a space;
Partitioned and formed by Helmholtz resonance frequency
A closed space silencer that silences noise and a silencer
The cut air is formed along the partition plate and
An air flow passage leading to the discharge port, a partition plate is movably provided so as to change the volume of the closed space of the muffling chamber, and the flow hole is variably changed so as to change the cross-sectional area of the flow hole of the partition plate. To form an air flow passage for the basic silencing chamber
Move the wall along the direction of airflow between the inlet and outlet.
A silencer characterized by being provided movably . 4. At least two partition plates having flow holes
The space inside the basic sound deadening room is partitioned by these partition plates.
Multiple pieces of silencing chambers in opposing positions on both sides sandwiching the air passage
4. The muffler according to claim 3, wherein the muffler is formed . 5. A mode detecting device for detecting a standby or operating state of a device, a partition plate moving control device for controlling a moving amount of a partition plate with respect to the operating state, and moving the controlled partition plate. muffler device according to claim 3 or 4, characterized in that provided between the partition plate moving device for. 6. A noise amount detecting device for detecting a noise amount of a device, a partition plate moving control device for controlling a moving amount of a partition plate according to the noise amount, and a partition plate for moving the controlled partition plate. 4. A moving device , comprising:
The muffler according to 4 or 5 . 7. A distribution wall movement control device for controlling an amount of movement of a distribution wall formed in an air flow passage in an air circulation direction, and a distribution wall movement device for moving the controlled distribution wall. The muffler according to any one of claims 3 to 6 , characterized in that: